Trailer type mole unit

ABSTRACT

Mole apparatus useful with mobile tractor equipment, such as mounted rippers, for placing flexible conduit beneath earth surfaces that are of irregular contour. A flexible towing connection extends rearwardly from the lower end of a ripper tooth to engage the lower forward end of the mole structure. The mole has spaced exterior surfaces, interior plates and guide rollers providing a protected path through which the conduit moves from an above-ground point of introduction to a point of discharge beath the earth surface. Where metal or other rigid pipe is to be placed or where large pipe is placed with an increased depth of earth cover, the mole is advantageously pivoted or longitudinally bendable about lower horizontally transverse axes. Support wheels maintain the mole in upright position, and power means are provided for regulating the position of said wheels to govern the placement depth for the conduit. Power means additionally and selectively regulate the operative length of said tow connection.

United States Patent [1 1 Coffey 1 Nov. 26, 1974 1 TRAILER TYPE MOLE UNIT [76] Inventor: Eugene R. Coffey, PO. Box 1267,

Montrose, Colo. 81401 [22] Filed: Nov. 2, 1973 [21] Appl. No: 412,213

Primary Examiner]acob Shapiro Attorney, Agent, or Firm-C. B. Messenger [5 7 ABSTRACT Mole apparatus useful with mobile tractor equipment, such as mounted rippers, for placing flexible conduit beneath earth surfaces that are of irregular contour. A flexible towing connection extends rearwardly from the lower end of a ripper tooth to engage the lower forward end of the mole structure. The mole has spaced exterior surfaces, interior plates and guide rollers providing a protected path through which the conduit moves from an above-ground point of introduction to a point of discharge beath the earth surface. Where metal or other rigid pipe is to be placed or where large pipe is placed with an increased depth of earth cover, the mole is advantageously pivoted or longitudinally bendable about lower horizontally transverse axes. Support wheels maintain the mole in upright position, and power means are provided for regulating the position of said wheels to govern the placement depth for the conduit. Power means additionally and selectively regulate the operative length of said tow connection.

21 Claims, 14 Drawing Figures :5 61974 PATENTEL WHEN a 3.849.999

FIG; 5

PATENTE HSVZBIBH SHE W a 3.849.999

1 TRAILER TYPE MOLE UNIT BACKGROUND OF THE INVENTION In previous patents issued to the present inventor, mole units are provided that facilitate the emplacement of various types of flexible conduit. The earlier mole attachments disclosed in the previous US. Pat. Nos. 3,344,615 and 3,429,134 are preferably used with trail I mounted ripper apparatus. More than a thousand miles of pipe have by now been placed utilizing the previous types of equipment. Prior beneficial operations include the placement of six-inch plastic pipe at depths providing a seven-foot earth cover. In the accomplishment of such earlier installations, the novel mole movements pattern resulting from the use of a low pivot attachment between the ripper tooth and mole and the trailing characteristics for trail mounted type rippers have prevented breakage of the pipe being placed. The number of leaks experienced when the lines are initially tested or after subsequent and continued usage has been quite low. The same beneficial results have not been obtainable by others when mole units are used with the more extensively available tractor mounted rippers. The abrupt changes in ripper tooth depth when the mounting tractor encounters changes terrain conditions apparently causes excessive stressing and breakage of the conduit being placed.

SUMMARY OF THE INVENTION In order to improve the efficiencies of underground pipe placement where mounted rippers are to be used and, further, to provide an increased capability so that the more rigid types of metal pipe or pipe of larger size can be placed at increased depth, the present invention provides a mole unit that can be joined to the ripper tooth of mounted ripper equipment to follow therebehind in a trailer type arrangement. The trailer mole is joined to the bottom of the ripper tooth by a flexible tow connector engaged to the lower front end of the mole. Support wheels are provided to maintain the mole in a vertically oriented position and to adjust the earth penetration depth of the mole. The flexible tow connection courses along the bottom ofthe earth structure cut and disturbed by the ripper tooth, and the mole itself is drawn by the tow connection along the previously cut path. Inclined spoon bill type surfaces on the mole keep the unit at the bottom of the ripped path. The mole is isolated by the flexible connection from any erratic or violent up and down movements of the mounted ripper as the tractor courses along a supporting earth surface that may be of irregular contour and along paths where boulders or similar sharp raises or declivitiesmay be encountered. In further embodiments of the invention the effective length of the flexible tow connection may be selectively changed through use of power apparatus that adjusts the trailing distance for the mole. Where metal pipe is to be installed or where larger sizes of conduit are to be placed, mole extension components provide features permitting longitudinal bending of the mole about lower transverse axes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation in partial section showing operative features of the invention,

FIG. 2 is a side elevation illustrating one mole embodiment,

FIG. 3 is a top plan view of the mole unit shown in FIG. 2,

FIG. 4 is a partial enlarged top view showing an auxiliary conduit placing attachment,

FIG. 5 is a side view of the attachment shown in F IG.

FIG. 6 is a side elevation in partial section showing additional features of the mole embodiment,

FIG. 7 is a top view of enlarged size showing a lateral ledge ripper applied to the mole,

FIG. 8 is a side elevation further illustrating the ledge ripper of FIG. 7,

FIG. 9 is a cross-sectional elevation providing a conduit emplacement representation,

FIG. 10 is a side elevation showing a mole embodiment of extended length providing vertical flexibility,

FIG. 11 is a diagrammatic side view showing use of such extended mole coursing along a raised earth structure,

FIG. 12 is a diagrammatic side view showing use of such extended mole coursing along a depressed earth structure,

FIG. 13 is a side cross-sectional elevation showing a further embodiment of the invention, and

FIG. 14 is a side cross-sectional elevation showing an additional modified embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Features of a first embodiment of the invention are shown in FIGS. 1 through 9. Such embodiment provides a mole attachment or mole unit 12 that is adapted to be trailed behind a track-laying tractor 13 which carries a mounted ripper system 14. A flexible tow connection, such as a chain or the cable 16, interconnects the forward end 17 of the mole l2 and the bottom 18 of a ripper tooth 19. The tow connection 16 is preferably flexible so that it may bend as it is drawn through disturbed earth structures 21 that have already been ripped by the ripper tooth 19, its lower ripper point 22 and/or by the depth control fins 23 disposed angularly at the bottom of the ripper tooth. Since the mounting tractor 13 itself may be connected to other towing tractors by a cable 24 or by various types of tandem interconnections now used for joining a plurality of tracklaying tractors together, a substantial draw bar pull is exerted on the ripper mount 14 for transmission to the ripper tooth l9. Undisturbed earth structures 26 that may include rocks, boulders, shales or even sandstones can be ripped by such arrangement to provide a loosened earth structure 21 behind the ripper tooth 19. The mole unit 12 is drawn along such predisturbed path by the flexible connection 16. The inclined flat surface 27 on the mole 12 and impingements thereof against the ripped earth structure causes the lower bottom 28 of the mole to stay in contact with the surface defined by the prior passage of the ripper tooth 19. The mole 12 is itself of near hollow construction, and, accordingly, flexible conduits, such as the pipe 29, may be introduced into the interior of the mole for passage therethrough to a point of discharge at the rear lower end 31 of the mole 12. The depth of penetration for the ripper tooth 19 is controlled by the positioning of the connector pins 32 of the ripper mount and mating holesor receptacles 33 disposed in vertically spaced positions along the length of the tooth 19. The penetration depth for the ripper tooth is also controllable through actuation of the mount cylinders 34 which can be used to lower the ripper tooth to a full penetration depth or alternately to raise the tooth to a position where the forward point 22 is out of contact with the supporting earth.

The described tow arrangement is highly beneficial when compared to other systems for mounting and towing a mole implant attachment when used with mounted type rippers. Where mole attachments are directly attached to a mounted ripper by pivot means disposed at variously spaced vertical positions at the rear of the ripper, moles of substantial length will be sub-- jected to rather abrupt vertical movements as the tracks of the mounting tractor 13 move over raised obstructionsor across short declivities. The use ofa single pivot disposed at the lower end of the mole and the ripper tooth in keeping with the teachings of the mentioned prior art patents minimizes the difficulties experienced but does not fully eliminate the problem especially where larger sizes of plastic tubing or pipe are being placed or where other less flexible conduits are 7 to be buried at intermediate and excess depths. The

mole attachments to be used with larger sized pipe or more rigid conduit structures are necessarily longer to accommodate even the medium radius bends to which the pipe may be subjected. With long mole units the rear exit end will .be subjected to increase displacements and abrupt movement patterns when the mole is connected to a tractor mounted ripper. The mole attachment 12 shown herein is moved through preripped earth structures by the flexible tow connection 16, and the mole tends to stay in contact with the bottom of the ripped path. Up and down movements of the forward end 17 are avoided, and similarly the rear or exit end 31 is not subjected to abrupt movement patterns. Accordingly, the pipe or conduit 29 being placed will uniformly be discharged at or near the bottom of the ripped pathway.

Since only the flexible connection 16 provides towing or guidance forces for the mole, it is necessary to provide auxiliary stabilization for the mole. A wheel mount system is provided to hold the mole at all times in near upright position and to selectively elevateor lower the mole with respect to a ground surface. Features of a wheel mount system 30 are shown in FIGS. 1 and 2. A

support frame 36 is provided at the top of the mole l2.

The support frame is divided centrally to provide an upwardly open entrance channel 37 into which the pipe 29 being placed is introduced. Separate hydraulic cylinders 38 are disposed on opposite sides of the frame 36 for interconnection to crank arms 39 for the wheel mount apparatus 30. The crank arms 39 are joined to torque tubes 41 which fit over laterally extending pivot axles 42.'Action arms 43 are joined to the torque tubes 41 for movement therewith. Accordingly, as the shafts 44 of the hydraulic cylinders 38 are extended, the crank arms 39 will be rotated to move the action arms 43 to adjusted positions. Support wheels 46 are disposed on the stub axles 47, which are mounted on the free ends of the action arms 43. As the wheels are lowered with respect to the mounting frame 36, the entire mole 12 will be elevated. The mole can be brought to a full above-ground position as shown in FIG. 2, and towing eye 48 at the forward end 17 of the mole 12 can be coupled to a towing tractor or truck to be moved to any required alternate work sites. Desirably, the mole 12 will be substantially balanced fore and aft and side to side when the wheels are in the lowered configuration shown in FIG. 2. When properly balanced, mole units of substantial weight can be moved along roads and highways by relatively small trucks or tractors. When the mole is to be moved to other work sites, hydraulic supply hoses 49 can be separated at a quick disconnect connector 51 that may be mounted on the towing tractor 13 or on the mole frame 36 as illustrated. These hydraulic supply lines 49 are at time of use for the mole l2 interconnected to a control valve 52 adjacent the operators position on the tractor. With this arrangement the operator can adjust the position for the supporting wheels 46 when the mole is being introduced into the ground or removed therefrom or to make depth adjustments during the pipe laying process. The provision of separate hydraulic cylinders and crank arms for rotation on a non-moving pivot axle 42 makes it possible to provide individual control for the separate action arms 43 and wheels 46 if pipe is to be laid along a side slope.

A cross-sectional representation of the mole attachment 12 described is shown in FIG. 6. In this drawing it it seen that an internal frame work of metal diaphragm segments 53 interconnects the exterior sidewalls 54. Preferably the angled diaphragm segment 53 should extend from the front rearwardly inclined plate 56 to the rear discharge opening 57. Such rear discharge opening is in part defined by the lower edge 58 of the sidewalls 54 and by the rear truncated edge 59 of side plates 54. A guide passage for the pipe being placed extends from entrance opening 37 and is defined as it passes rearwardly through the mole attachment by the diaphragm plate 53 and by segmental plates 61 which, together with permanent guide rollers 62 63 and 64, serve to prevent abrasion of the pipe being implanted. At the rear a pivot mounted guide roller 66is biased toward contact with the pipe being placed by a spring 67. A partial front plate 68 is removably positioned at the forward end ofthe attachment 12 to be selectively held in such position by a fastener plate 69. The plate 68 can be removed to provide a larger entrance opening when less bendable types of pipe, such as pipe made of more rigid materials or pipes of larger flow diameter or of thicker wall sections are used.

In addition to the main passage provided through the mole unit 12 to facilitate placement of a main conduit, FIG. 6 shows the provision of an auxiliary guide chute 71 that may be used in connection with the simultaneous placement of auxiliary conduits or cables. FIGS. 1 through 9 illustrate features of such auxiliary conduit emplacement apparatus. At many work sites where mole implant apparatus is to be used, there is often more than one conduit system to be installed. Water lines, natural gas supply lines, electrical power cables and telephone services are often all required when housing installations are being made. At all installations at least one large size conduit is usually required. Other household type supplies may be of lesser size. If water lines are installed, they usually will be of the largest size, and the required depth of placement is usually greatest for water lines to prevent freezing or breakage of the lines due to soil stresses or surface loadings. Many communities now permit the installation ofa plurality of services along a single right-of-way. Where trench digging procedures are used, it is usually required that separate utilities be disposed at different elevations or even in laterally spaced positions. Gas and electrical conduits can often be placed in a single ditch excavation together with a water line if the ditching procedure can provide a separate bench support for the auxiliary utilities so all of the lines will be adequately supported by undisturbed earth structure. At some cations supporting benches must be provided at laterally spaced positions and at separate line elevations. Operations with the present apparatus indicate that multiple utility installations can be made through use of the large scale ripper equipment disclosed herein. Mole apparatus of the type described has been used to place plastic water lines in northern climates at depths providinga seven-foot cover in order to prevent freezing of such lines. If a large conduit, such as a water pipe, is to be placed at depths of 4 to 7 feet, little additional power or work is required to simultaneously install auxiliary conduits. FIG. 9 illustrates the type of installation that can be made and that will fully satisfy the requirements of design engineers concerned with utility placement.

In FIG. 9 the previouslydisturbed earth structure 26 has been cut by the passage of a ripper tooth 19 and mole through the zone 76. A pipe conduit 72 has been placed at the bottom of the ripped section. If wing attachments are provided to extend outwardly from the side plates 54 of the mole attachment 12, the disturbed zone can be laterally extended, as shown at 73 and 74, to provide support benches 75 and 77 adapted to receive and support auxiliary conduits 78 and 79. Main conduit 72 and the auxiliary conduits 78 and 79 could represent a water main 72, a gas line 78 and an electric power conduit 79. The same illustration could also be representative of an installation for a main co-axial cable with auxiliary ground cables therefor or of other utility installations.

If auxiliary cables are to be placed along the same ripped pathway, support bench cutting elements will be applied to the mole 12. A lateral cutter element 81 is attached to the front of the mole l2, and an auxiliary conduit placement element 91 is attached to the rear of the mole at an elevation corresponding to the elevation for the lateral cutter 81 and at a position communieating with the auxiliary conduit chute 71.

Construction features for the lateral cutter element 81 are shown in enlarged detail in FIGS. 7 and 8. In these FIGS. the cutter element 81 is shown at a position extending across the inclined surface 27 at front plate 56 and laterally outward from the mole side plates 54. A plow type point 82 is provided at the intersection of angularly disposed segment 83 and a rearwardly and upwardly extending wing surface 84. The internal surfaces of segment 83 and of wing surface 84 closely engage support blocks 86 fastened in permanent position on the mole side plates 54. With this arrangement the cutter element 81 can be placed on the blocks 86, and it will be held by a wedging action in its desired position by the continued impingement of such attachment against ripper disturbed earth. When auxiliary cables are not being placed, hammer blows directed against the rear edge 87 of cutter 81 will be effective to remove the attachment.

Features of the rearwardly disposed auxiliary conduit placement elements 91 are best shown in enlarged detail in FIGS. 4 and 5. This auxiliary attachment is selectively positioned on the mole 12 by use of a single through-bolt 92. This bolt extends through paired side plates 93 which are of a size to engage the outside surface of mole side plates 54. Auxiliary conduit placement attachment 91 is essentially a hollow box like structure providing an internal passage that widens vertically to a dimension corresponding with the outside dimension for the auxiliary guide chute 71. When in the proper position, the attachment 91 will surround the exit opening 94 of such guide chute 71. Accordingly, any auxiliary conduits introduced through the guide chute 71 will be discharged into the interior of the attachment 91. Paired exit outlets 98 and 99 are separately provided to guide and position the auxiliary conduits 78 and 79 to positions on their respective support benches and 77. Such support benches are, of

course, precut by the side flaring wing portions 84 of the front attachment 81 and are reopened by the rearwardly and upwardly inclined ramp surfaces 95 and 97 provided by the attachment 91 at positions coordinated with the positioning for conduit outlets 98 and 99. A central divider 101 is provided within the attachment 91 to guide the auxiliary conduits into their respective divergent positions.

FIGS. 10 through 12 illustrate mole extension apparatus that can be used together with the mole 12 where the more rigid types of pipe or conduit are to be installed. Natural gas, petroleum and water lines are often extended across great distances. When lines are subjected to higher flow pressures or increased soil stress, metal pipe is frequently used. Metal pipe, as well as some types of plastic pipe of larger diameter, is rela tively rigid and the maximum bend arcs permissible would prevent placement through use of a mole attachment that was itself of somewhat rigid construction. In order to accommodate such rigid pipe and pipe of larger diameter and to still provide an implant system that can be used for pipe installation along ground structures of irregular contour, mole extension components are provided for cooperative use with the basic mole attachment 12 heretofore described. A forward extension 102 having a towing eye 108 is positioned forwardly of the mole 12 and interconnected to an intermediate extension 112. The forward extension 102 has side plates 104 that extend past and over the side plates 114 for the intermediate extension 112. A pivot 103 interconnects the extensions to provide relative pivoting movement of the forward extension 102 with respect to the intermediate extension 112 in a vertically oriented plane. A further pivot type connection 113 is disposed adjacent the bottom of mole extension 112 for connection to the towing eye 48 of mole 12. As in the prior instance, the side plates 114 of the intermediate extension 112 cover and slide reciprocally over and along the side plates 54 for the mole: 12. When the mole extensions 102 or 112 are joined to the mole attachment unit 12, the forward partial] front plate 68 as shown in FIG. 6 will be removed so that the entrance opening is expanded. With this arrangement a pipe or other conduit 29 may be strung through the combined mole unit along a line as indicated in FIG. 10. The support axles and wheels 46, etc. can still be used when the combined mole is to be raised. Actually the wheel mount system will in such circumstances raise the rear mole l2 and the forward towing eye 108 can be directly connected to the ripper tooth 19 to raise the forward end of the combined unit. Movement limiting stops 106 and 107 can be provided on the extensions and mole l2 to limit the telescoping or sliding movement of the outermost side plates with respect to the plates of the following mole or extension unit.

With the arrangement described the combined and extended mole may still be beneficially used to make installations of rigid types of pipe or conduit along earth structures of irregular contour. Installation over humped terrain is shown in FIG. 11, while installation across a depression or ravine is shown in FIG. 12. For all such usage the provision of a connector, such as towing eye 108, at the lower end of the combined mole assembly will tend to keep the bottom of the mole units in position along the bottom of the earth ripped or disturbed by the ripper tooth. The vertically oriented flexibility will further prevent abrupt movements of the discharge end 31 for the mole attachment l2, and, accordingly, severe abrasion or breakage of the pipe will be avoided. The pipe will also at all times be placed with a depth of cover sufficient to comply with engineering and installation requirements.

FIG. 13 illustrates a further embodiment of the invention providing a tow connection or cable 116 that can be of selectively adjustable length. A hydraulic cylinder 118 is shown disposed within the mole 122. The cylinder is connected by hydraulic lines 119 to a quick disconnect supply 51. Actuation of the hydraulic system will then power extension and/or retraction of the cylinder shaft 121 to move a crosshead pulley 123 to extend or retract the flexible tow cable 116. One end of cable 116 is anchored to the mole 122 or to the hydraulic cylinder 118 by an anchor 124. A hydraulic accumulator 126 can be provided in the system for the purpose of absorbing shock loadings that might otherwise tend to damage the tow cable or the mole attachment or other associated equipment. Use of this hydraulic system can, of course, control the effective length of the towing cable 116 in order to shorten or extend the working distance between the mole 122 and the ripper tooth 19. This powered extension feature will have many advantageous uses during actual implant operations. The cable can be extended or shortened to provide increased tractive power as required, since the tractor can be moved past obstructions or areas of loose soil that would impair or lessen the draw bar pulling capability for the tractor 13 or the other tractors that may be interconnected thereto by the forward cable 24. Similarly, the cable 116 can be extended or retracted to provide clearance for the use of auxiliary digging equipment that is often used to remove large boulders or other underground obstructions from the implant pathway to avoid damage to the relatively thin side plates ofthe mole unit. Without such extension features the towing tractors sometimes need to be disconnected from the mole or the mole itself has to be raised out of the earth so that obstructions can be cleared. Job site conditions can often require disruption or discontinuance of the mole implant operations where difficult soil conditions are encountered if the mole itself is moved without a corresponding continuance of the pipe implanting functions. Where a flexible tow connection, such as even the cable 16, is used the tractor units can be backed up and moved without causing a corresponding movement backward of the following mole. If the towing cable itself can be extended and retracted as shown in FIG. 13, an increased freedom for independent movement of the tractor and mole is possible. With the system shown in FIG. 13 operations need not be discontinued even though extremely poor soil conditions are encountered. The tractive equipment can with such system be parked to provide a deadman anchor, and the mole can be moved along its intended course by successive extensions and retractions of the tow cable 116.

A further development providing a tow cable of adjustable length is illustrated in FIG. 14. In this embodiment of the invention the cable 136 extends through a forward opening 134 in the mole 132 and thereafter courses over a pulley 133 disposed within the mole 132. The cable 136 is by a succession of pulleys and guideways interconnected to the normally anchored end 139 of a hydraulic cylinder 138 that is interconnected to the support wheel crank arms 39. The cylinder 138 is normally used for moving the support wheels 46 as previously described. Once the wheels are moved to a full elevated position and the mole is at a full penetration depth in the earth, the wheels 46 and the crank arms 39 may be locked in place. A pin at the normally anchored end 139 of the hydraulic cylinder 138 can then be removed to free such anchored end. Actuation of the hydraulic cylinders will then cause extension of the cylinder housing itself, and the cable 136 attached to such housing will, accordingly, be retracted thereby providing the desired effective shortening of the tow connection 136. With this arrangement the hydraulic cylinders and the associated control equipment have multiple usage, and the hydraulic cylinders are kept at an elevated and above-ground position.

Where an adjustable tow connection is provided, the operative cable length can be changed to meet the requirements of various job site locations. Where flat level ground is to be crossed, the cable could be shortened to an operative length less than the penetration depth for the ripper tooth itself. Usually a best operating length that will avoid abrupt movements of the mole would be in excess ofa distance corresponding to the penetration depth for the ripper tooth. Longer effective lengths for the tow connection will usually be used where raises and declivities are to be encountered. Where flexible tow connections or cables of fixed length are to be used, such connections should usually be at least as long as the expected maximum penetration depth for the ripper tooth. Where the tow connection is longer than the penetration depth, the ripper tooth can be raised out of the earth without disturbing or moving the mole unit. When raised to such position, the ripper can be disconnected for independent use, such as preripping operations or to facilitate the clearing of obstructions. Subsequently, the ripper can be reconnected and conduit implant operations can be resumed.

In addition to providing an arrangement where the towing tractors can be connected or interconnected to the mole implant unit at will and without disturbing the conduit placing functions of the mole unit, the present disclosure provides an overall system that will give an improved conduit placing result. Where a flexible tow connection is used, violent or abrupt movements of the mole are avoided, and the pipe is not subjected to the lateral or vertical forces that will cause immediate breakage or that will subject the pipe to stresses that will result in subsequent leakage or problems. The ripper tooth for a mounted ripper system is often moved abruptly through erratic patterns as the tractor moves over and across irregular terrain. Though such undesirable movement patterns can, in part, be corrected by operator manipulations of the tooth mounting apparatus, such effects cannot be eliminated and the pipe being implanted by a mole that is closely attached to the ripper tooth can be broken or damaged.

The flexible tow connection also works beneficially with other features of the described apparatus to pro-. vide an improved bed of earth to receive and surround the placed pipe. The fins 23 on the sides of the ripper tooth help to hold the tooth downwardly in the ground, and they also operate to elevate rock and coarse materials upwardly and away from the ripper point 22 and lower end of the ripper tooth. While rock and larger pieces are elevated by the fins 23, dirt and other materials of small size fall downwardly into the bottom of the ripped path. The forward surface 27 for the mole unit 12 again clears the ripped path, and the bottom 28 of the mole, as shown in FIG. 1, generally stays at a slight elevation above the lowermost area disturbed by the ripper tooth point 22. With this arrangement the pipe being placed is deposited on a bed of essentially fine materials that have been slightly prepacked by the bottom 28 of the mole and that will, accordingly, provide good support for the pipe in place. The materials that subsequently fall to surround the pipe are likewise of finer particle size; accordingly, the pipe will not be damaged by the impact of falling materials. A pipe that is surrounded by finer materials will not be as subject to damage by reason of subsequent soil stresses that are concentrated and applied at a point rather than being distributed along the pipe. Any sharp rocks or other materials that might provide a fulcrum at the bottom of the ditch that would be in contact with the pipe are covered by the loose materials in the bottom of the ripped path, or they are substantially levelled by passage of the bottom of the mole itself.

In order to minimize the occurrence of fulcrum breaks when pipe is being placed in soils or shales having sharp edged rocks, it has previously been found desirable to interconnect the mounted ripper tooth and the mole unit so that the mole unit will trail the ripper tooth at a position two or more inches above the lower extent of the ripped path. With the present apparatus a most beneficial placement depth can be derived by adjusting the aboveground positioning of the support wheels 46 and also by changing the point of lower attachment for the tow connection 16 at the bottom of the ripper tooth 19.

The same bedding advantages are also provided in connection with the placement of the auxiliary conduits. The rearwardly and upwardly extending wings 84 of the lateral cutter element 81 disposed at the front of the mole similarly serves to elevate coarse materials so that the auxiliary conduits will be bedded in loose materials on their respective support benches. The action of the front wings 84 and the rear inclined ramp surfaces 95-97 provide a dual displacement feature corresponding to that of the control fins 23 and the front inclined surface 17 ofthe mole 12. Where the coarse materials are disturbed and elevated and then subsequently elevated again, finer bedding material characteristics are noted. This beneficial result could be derived from the soil contacting two disturbing surfaces one after the other and thus tending to break up coarse materials in addition to the dual elevating aspects ofthe present equipment. With this trailer type of mole it has in general been noted that the ripped path itself is substantially similar to that derived when a pipe implant course is initally preripped before the subsequent passage of a ripper tooth and close coupled mole unit.

I claim:

1. Mole apparatus for use with mobile tractor equipment to place conduit beneath earth surfaces that may be of irregular contour wherein a tractor mounted ripper tooth with separate depth control is provided comprising a separate mole implant unit for use behind the said ripper tooth of operative height whereby a portion of the mole unit is adjacent or above the earth surface for all selected penetration depths of said ripper tooth and mole, said mole unit having from andside plates providing an entrance opening at a position above the earth surface for introduction of a main conduit and a guide passage therethrough for directing said conduit along a path to the bottom of said mole whereby said conduit is deposited and placed at the bottom of the earth structure disturbed by the ripper tooth and mole unit, aleading edge on said mole unit disposed at a rearwardly inclined angle upwardly from the bottom of said mole, a tow connection for extension between the bottom of said ripper tooth and the front lower bottom of said mole for the transmission of towing force from said ripper tooth to said mole unit, :said tow connection being inclusive of means flexibly interconnecting said ripper tooth and mole unit whereby said mole is adapted for independent movement and rotation with respect to horizontal and vertical axis of reference, and stabilization means interconnected to said mole for engagement with the surface of the supporting earth for holding said mole in substantially vertically oriented positions as the ripper tooth and mole are moved over irregular earth surfaces.

2. The mole apparatus of claim 1 wherein said tow connection is of length corresponding to at least the penetration depth for said ripper tooth.

3. The mole apparatus as set forth in claim 1 and further comprising powered depth control apparatus for regulating the positioning of said stabilization means.

4. The mole apparatus as set forth in claim 3 and further comprising wheel mountings for said stabilization means.

5. The mole apparatus as set forth in claim 3 and further comprising hydraulic cylinders providing the depth control for said stabilization means.

6. The mole apparatus as set forth in claim 5 and further comprising separately operable stabilization means on opposite sides of said mole unit, and separate means for the selective positioning of said separate stabilization means whereby said stabilization means is cooperatively positionable to maintain the mole in vertically oriented position as the ripper tooth and mole are moved along laterally inclined and sidehill surfaces.

7. The mole apparatus as set forth in claim 1 wherein said tow connection is itself flexible to accommodate bending movement intermediate said ripper tooth and mole.

8. The mole apparatus as set forth in claim 7 wherein said tow connection is provided by a cable.

9. The mole apparatus as set forth in claim 7 and further comprising means for adjusting the length of said tow connection.

10. The mole apparatus as set. forth in claim 9 wherein said length adjusting means comprises a cable system and hydraulic powered apparatus for regulating the effective length of said cable.

11. The mole apparatus as set forth in claim wherein a hydraulic cylinder is provided for adjusting the length of said tow connection cable.

12. The mole apparatus as set forth in claim 11 wherein said hydraulic cylinder is additionally useful to provide depth control for regulating the positioning of said stabilization means.

13. The mole apparatus as set forth in claim 1 wherein the tow connection intermediate the ripper tooth and said mole unit is inclusive ofa mole extension component andv further comprising pivot means interconnecting said mole unit and said mole extension whereby said mole unit and extension are pivotally movable one with respect to the other in a vertically oriented plane.

14. The mole apparatus as set forth in claim 13 .wherein said mole extension additionally provides a through passage for the reception and guidance of a main conduit whereby the total arcs of curvature through said mole unit and extension are lessened for the accommodation of more rigid conduits.

15. The mole apparatus as set forth in claim 14 wherein the front plate for said mole unit is selectively removable to increase the size of the entrance opening for said mole unit when more rigid conduit is to be placed.

16. The mole apparatus as set forth in claim 14 wherein a plurality of mole extensions are provided for interconnection intermediate said mole unit and ripper tooth and further comprising pivot connections between the separate mole extensions and the mole unit to accommodate vertical bending of said mole apparatus.

17. The mole apparatus as set forth in claim 1 wherein said mole front plate is disposed along said leading edge and further comprising angularly disposed fins on said ripper tooth and extending outwardly and upwardly from the forward bottom portion thereof whereby coarse materials disturbed by the ripper tooth are displaced upwardly and rearwardly as the tooth passes along a ripped path and wherein the front plate and leading edge of said mole are disposed rearwardly from said ripper tooth a distance corresponding to at least the penetration depth for said ripper tooth whereby materials disturbed by said ripper tooth and fins will settle in the ripped path before recontact and re-elevation by said inclined front plate whereby coarse materials are moved away from positions surrounding the emplaced conduit.

18. The mole apparatus as set forth in claim 1 wherein said mole unit is additionally useful for the simultaneous placement of main and auxiliary conduits and further comprising a cutter element positioned at the front of said mole unit at an elevation above the bottom of the mole and an auxiliary conduit placement attachment disposed at the rear of said mole at a level corresponding to the level for said front cutter element, and an auxiliary guide chute provided by said mole apparatus whereby an auxiliary conduit is delivered from an above ground position to said auxiliary conduit placement attachment.

19. The mole apparatus as set forth in claim 18 wherein said front cutter element and said auxiliary conduit placement attachment extend laterally and outwardly from said mole unit to provide a ripped path of wider extent corresponding with the positioning of said elements.

20. The mole apparatus as set forth in claim 19 wherein said front cutter element and rear auxiliary conduit placement element are removably attached to said mole unit for extension outwardly and laterally from each of the sides thereof.

21. The mole apparatus as set forth in claim 20 and further comprising rearwardly and upwardly extending surfaces for said front cutter element and rear auxiliary conduit placement element whereby materials in the path ripped by said elements are initially displaced upwardly and rearwardly by the inclined surfaces of said front cutter element and are subsequently recontacted and re-elevated by the inclined surfaces of said auxiliary conduit placement element whereby coarse materials are moved away from positions surrounding the em- 

1. Mole apparatus for use with mobile tractor equipment to place conduit beneath earth surfaces that may be of irregular contour wherein a tractor mounted ripper tooth with separate depth control is provided comprising a separate mole implant unit for use behind the said ripper tooth of operative height whereby a portion of the mole unit is adjacent or above the earth surface for all selected penetration depths of said ripper tooth and mole, said mole unit having front and side plates providing an entrance opening at a position above the earth surface for introduction of a main conduit and a guide passage therethrough for directing said conduit along a path to the bottom of said mole whereby said conduit is deposited and placed at the bottom of the earth structure disturbed by the ripper tooth and mole unit, a leading edge on said mole unit disposed at a rearwardly inclined angle upwardly from the bottom of said mole, a tow connection for extension between the bottom of said ripper tooth and the front lower bottom of said mole for the transmission of towing force from said ripper tooth to said mole unit, said tow connection being inclusive of means flexibly interconnecting said ripper tooth and mole unit whereby said mole is adapted for independent movement and rotation with respect to horizontal and vertical axis of reference, and stabilization means interconnected to said mole for engagement with the surface of the supporting earth for holding said mole in substantially vertically oriented positions as the ripper tooth and mole are moved over irregular earth surfaces.
 2. The mole apparatus of claim 1 wherein said tow connection is of length corresponding to at least the penetration depth for said ripper tooth.
 3. The mole apparatus as set forth in claim 1 and further comprising powered depth control apparatus for regulating the positioning of said stabilization means.
 4. The mole apparatus as set forth in claim 3 and further comprising wheel mountings for said stabilization means.
 5. The mole apparatus as set forth in claim 3 and further comprising hydraulic cylinders providing the depth control for said stabilization means.
 6. The mole apparatus as set forth in claim 5 and further comprising separately operable stabilization means on opposite sides of said mole unit, and separate means for the selective positioning of said separate stabilization means whereby said stabilization means is cooperatively positionable to maintain the mole in vertically oriented position as the ripper tooth and mole are moved along laterally inclined and sidehill surfaces.
 7. The mole apparatus as set forth in claim 1 wherein said tow connection is itself flexible to accommodate bending movement intermediate said ripper tooth and mole.
 8. The mole apparatus as set forth in claim 7 wherein said tow connection is provided by a cable.
 9. The mole apparatus as set forth in claim 7 and further comprising means for adjusting the length of said tow connection.
 10. The mole apparatus as set forth in claim 9 wherein said length adjusting means comprises a cable system and hydraulic powered apparatus for regulating the effective length of said cable.
 11. The mole apparatus as set forth in claim 10 wherein a hydraulic cylinder is provided for adjusting the length of said tow connection cable.
 12. The mole apparatus as set forth in claim 11 wherein said hydraulic cylinder is additionally useful to provide depth control for regulating the positioning of said stabilization means.
 13. The mole apparatus as set forth in claim 1 wherein the tow connection intermediate the ripper tooth and said mole unit is inclusive of a mole extension component and further comprising pivot means interconnecting said mole unit and said mole extension whereby said mole unit and extension are pivotally movable one with respect to the other in a vertically oriented plane.
 14. The mole apparatus as set forth in claim 13 wherein said mole extension additionally provides a through passage for the reception and guidance of a main conduit whereby the total arcs of curvature through said mole unit and extension are lessened for the accommodation of more rigid conduits.
 15. The mole apparatus as set forth in claim 14 wherein the front plate for said mole unit is selectively removable to increase the size of the entrance opening for said mole unit when more rigid conduit is to be placed.
 16. The mole apparatus as set forth in claim 14 wherein a plurality of mole extensions are provided for interconnection intermediate said mole unit and ripper tooth and further comprising pivot connections between the separate mole extensions and the mole unit to accommodate vertical bending of said mole apparatus.
 17. The mole apparatus as set forth in claim 1 wherein said mole front plate is disposed along said leading edge and further comprising angularly disposed fins on said ripper tooth and extending outwardly and upwardly from the forward bottom portion thereof whereby coarse materials disturbed by the ripper tooth are displaced upwardly and rearwardly as the tooth passes along a ripped path and wherein the front plate and leading edge of said mole are disposed rearwardly from said ripper tooth a distance corresponding to at least the penetration depth for said ripper tooth whereby materials disturbed by said ripper tooth and fins will settle in the ripped path before recontact and re-elevation by said inclined front plate whereby coarse materials are moved away from positions surrounding the emplaced conduit.
 18. The mole apparatus as set forth in claim 1 wherein said mole unit is additionally useful for the simultaneous placement of main and auxiliary conduits and further comprising a cutter element positioned at the front of said mole unit at an elevation above the bottom of the mole and an auxiliary conduit placement attachment disposed at the rear of said mole at a level corresponding to the level for said front cutter element, and an auxiliary guide chute provided by said mole apparatus whereby an auxiliary conduit is delivered from an above ground position to said auxiliary conduit placement attachment.
 19. The mole apparatus as set forth in claim 18 wherein said front cutter element and said auxiliary conduit placement attachment extend laterally and outwardly from said mole unit to provide a ripped path of wider extent corresponding with the positioning of said elements.
 20. The mole apparatus as set forth in claim 19 wherein said front cutter element and rear auxiliary conduit placement element are removably attached to said mole unit for extension outwardly and laterally from each of the sides thereof.
 21. The mole apparatus as set forth in claim 20 and further comprising rearwardly and upwardly extending surfaces for said front cutter element and rear auxiliary conduit placement element whereby materials in the path ripped by said elements are initially displaced upwardly and rearwardly by the inclined surfaces of said front cutter element and are subsequently recontacted and re-elevated by the inclined surfaces of said auxIliary conduit placement element whereby coarse materials are moved away from positions surrounding the emplaced auxiliary conduit. 